#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
  int x,y,l,a,b,ans;
  cin>>x>>y>>l;

  if(x%l==0) a=abs(x)/l;
  if(y%l==0) b=abs(y)/l;
  if(y%l!=0) b=abs(y)/l+1;
  if(x%l!=0) a=abs(x)/l+1;
  if(y>=0){
  	if(x==0) ans=a+b;
  	else ans=a+b+1;
  }
  if(y<0){
  	ans=a+b+2;
  }
  cout<<ans<<endl;
}